Document: SHA-3-42-10

The roles of herbivory and other environmental factors on a flower color polymorphism.

STRAUSS, S.Y*

UC Davis, Davis, CA 95616 USA ¹

Abstract:
Flower color polymorphisms are traditionally thought to be maintained by selection from pollinators. In wild radish (Raphanus sativus) previous investigators showed that bee and fly pollinators exhibit different preferences for white-, yellow- and pink- flowered plants. Herbivory and other environmental factors may also act as selective agents in this system. Manipulations of plots of wild radish in the field included watering treatments, molluscicides, pesticides and controls. All treatments had effects on plant fitness, and there was a significant treatment by flower color interaction. That is, the relative fitness of the white- and yellow- flowered plants reversed in watering versus other treatments. In addition, surveys of flowers showed that flower-feeding thrips were significantly more dense in pigmented flowers than in white flowers. These results indicate that important selective agents on traits are not easily identified and that fluctuating selection due to changing environmental conditions may act to preserve the polymorphism in this system.

Keywords: herbivore, pollinator, polymorphism, selection

This abstract is being presented at: 9:15 AM in session:
Oral Session #26: Invertebrate Herbivore - Plant Interactions.